Pressure gauge



Aprll 26, 1927- H. CLARK PRESSURE GAUGE Filed Dec. 5, 1919 Patented Apr.26, 1927.

UNITED STATES PATENT OFFICE.

GEORGE H. CLARK, OF MELBOSE, MASSACHUSETTS, ASSIGNOR TO CROSBY STEAMGAGE 85 VALVE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAS-SACHUSETTS.

PRESSURE GAUGE.

Application filed December 5, 1919. Serial No. 342,816.

This invention relates to that well known type of pressure gauge inwhich a Bourdon spring tube is employed and in which the pressure isindicated by mechanism comprising a sector actuated by the spring tubeand in turn rotating a pinion on whose shaft 1s mounted an index handwhich indicates the pressures on a dial; with which combination it iscustomary to control the pinion shaft by a hair spring so arranged as totake up the backlash between the sector and the pinion; but it appearsthat such employment of the hair sprin is unsatisfactory as it producesa rotative force in the pinion shaft, not by means of a rotative couple,but by a single force acting in a certain direction and with a givenleverage, thereby producing irregularities or errors, of which the mostpronounced are indicated at points diametrically opposite on the gaugedial; and one serious result of all this is the necessity of making thedials, particualrly those of the larger gauges, individually, as astandard marked dial would not accurately indicate the pressures.

The object of the present invention is to do away with the hair springand to substitute therefor a spring acting directly through the sectorand producing a thrust which acts always in the same direction and onthe line of centres of the sector and pinion, thereby following a fixedlaw and making possible the employment of standard marked dials in allcases.

To accomplish this object I employ a triple sector comprising two outersectors relatively fixed and preferably made of one piece, to which thespring tube is indirectly attached, and a middle sector rotativelymounted between them on their common axis,

which three sectors engage the pinion; and,

The invention is illustrated by the accompanying drawings in which Fig.1 is a View of the dial reduced in size;

Fig. 2 is a view of the gauge with the case and dial removed;

Fig. 3 is a plan view looking in the direction of the arrow Fig. 2.

The gauge case 1, frame 2 encased therein. dial 3, index hand 4:, pinionshaft 5, pinion 6, and linkage 7 connecting the spring tube 8 with thesector 9 are all combined in a wellknown manner and need not bedescribed. The triple sector 9 comprises three sectors. namely, the twooutside sectors 9, 9 and the middle sector 9, all having a common axis10 journalled in frame 2 and all engaging the pinion 6; the sectors 9*,9 constituting a forked sector made of one piece and connected throughlinkage 7 with spring tube 8; and the middle sector 9 being engaged andcontrolled by the spring 11 affixed to the inner end 12 of the forkedsector 9 W.

I claim:

1. In a pressure gauge, in combination, a Bourdon spring tube; a sector;mechanism operatively connecting the spring tube with the sector; apinion engaged and actuated by the sector; and indicating means actuatedbv the pinion; the sector comprising a forked member, operativelyconnected with the spring tube, and a rotatively spring controlledintermediate member; and the members having a common axis and engagingthe pinion; together with the controlling spring.

2. A pressure gauge having, in combination, an operating tube, a toothedsector, operating connections between the tube and sector, indicatingmeans, a pinion connected therewith and meshing with the sector, and asecond sector having the same pitch and axis of rotation as the firstsector and also meshing with the pinion, and yielding connectionsbetween the two sectors for normally imparting a relative rotation tocause a close engagement of the teeth of the pinion and avoid backlashbetween the pinion and first-mentioned sector.

In testimony whereof I have aflixed my signature.

GEORGE H. CLARK.

